Air hammer with selective drill steel rotation



May 18, 1954 G. H. Fux-:HRER 2,678,636

AIR HAMMER WITH SELECTIVE DRILL STEEL ROTATION Filed July 14, 1953 2 Sheets-Sheet l JNVENToR.

armen/4? May 18, 1954 l G. H. FuEHRl-:R 2,678,636

AIR HAMMER WITH SELECTIVE DRILL STEEL ROTATION Filed July 14, 1955 2 Sheets-Sheet 2 es Qgyqqif 84 97 95 95' .p7/J6. 4 72 P 79 www,

Patented May 18, 1954 AIR HAMMER WITH SELE CTIVE DRILL STEEL ROTATION George H. Fuehrer, Downey, Calif., assignor to Thor Power Tool Company, Aurora, Ill., a corporation of Delaware Application July 14, 1953, Serial No. 367,931

11 Claims. (Cl. 121-7) This invention relates to an air hammer with selective drill steel rotation, and particularly to a relatively small pneumatically operated device which may be readily adapted, without disassembly of any parts, to eiect either hammer action alone or hammer action plus automatic drill steel rotation.

ln air hammers or drills, for example of the relatively small type used for general maintenance work, it is conventional to embody some means for effecting automatic rotation of the drill steel as it is hammered by the pneumatically operated piston. Although such rotation is highly desirable for many operations, for exn ample when the apparatus is used for drilling concrete and the like, there are several situations in which rotation is undesirable and in fact destructive to the effective operation of the tool. One such situation is in hole spotting, that is to say in the forming of a small initial hole preparatory to full-speed drilling action, since the spotting operation is facilitated if rotation is temporarily stopped. It will be evident that another such situation arises when the apparatus is employed with a tool having a single straight cutting edge, such as a chisel or chipping edge, since the rotation ci such an edge would necessitate a corresponding and opposite rotation of the hammer itself in order to maintain the cutting edge in proper relationship to the work. Although it u is possible, with conventional air hammers, to prevent drill steel rotation by disassembling the drill and removing the rotation ratchets or other elements, such an operation is highly time consuming and laborious and may result in the damaging or losing of parts. Furthermore, such a procedure only approaches practicality when the hammer is to be used Without drill steel rotation for long periods ci time, for example when the tool is to be used as a. chipping hammer, and is completely impractical when it is merely desired to prevent rotation for short periods of time such during hole spotting.

In view of the above factors characterizing the eid of air hammers, it is an object of the present invention to provide a highly simple and novel means by which the drill operator may selectively start or stop drill steel rotation merely by manually turning a knob or handle.

Another object of the invention is to provide a drill steel rotation release device in which the rotation pawls themselves are shifted longitudinally of the drilling apparatus to provide a cam action drawing the pawls out of contact with the associated ratchet teeth.v

An additional object is to provide a drill steel rotation release device which is mechanically operated independently of the air system for the hammer.

These and other objects and advantages of the invention will be more fully appreciated upon a reading of the following specification and claims considered in connection with the attached drawings to which they relate.

In the drawings:

Figure 1 is a longitudinal central section of a relatively small air drill or hammer embodying the present invention;

Figure 2 is a transverse section taken alongline 2--2 of Figure 1 and as viewed in the direction of the arrows;

Figure 3 is a horizontal section at line 3--3 of Figure 2;

Figure 4 is a fragmentary longitudinal section along line 4-4 of Figure 2 and illustrating one of the rotation pawls in operative position engaging a ratchet tooth; and

Figure 5 is a view, corresponding to Figure 4, but showing the rotation pawl in a longitudinally shifted, disengaged position at which drill steel rotation is no longer effected.

Referring to the drawings, and particularly to Figure 1, the apparatus may be seen to comprise an elongated cylindrical casing, indicated generally by the reference numeral I0, a distributing valve II mounted in the rear portion of casing il to direct air to opposite sides of a piston hammer I2 and thus eiect its forward and reverse movement, and a drill steel I3 projecting from the forward end of casing l0 for operating contact with the work during its percussion by the hammer. The casing I0 comprises, starting with the rear end of the drill or to the right as viewed in Figure 1, a grip handle I4, a rear cylinder i6, a distance piece I7, and a forward cylinder i8, all of these elements being maintained in axially abutting relationship as by side bolts I9 indicated in Figures 2 and 3. The illustrated drill steel I3 is of the hexagonal type embodying a collar 2| adapted to prevent the shank end 22 of the drill steel from penetratingexcessively into casing Il), the collar being also adapted to engage the for ward portion of a helical tension spring 23 which is mounted on forward cylinder I8 to prevent the drill steel from shifting out of position.

Distributing valve I I comprises a generally cup-shaped forward valve chest 25 having a plurality of ports 25 therein, a generally annular rear valvechest 2,6, a valve guide 2l mounted axially of the forward and rear valve chests, and

a valve element 28 slidably mounted on valve guide 21 for reciprocation between forward and reverse operating positions. The Valve chests 24 and 26, and valve guide 21, are locked in position between suitable seats in the rear end 'of cylinder I6 and in the forward portion of grip handle I4. It will be noted that valve guide 21, and also piston hammer I2, are axially bored to receive a fluid tube 29 adapted to transmit air, from an inlet passage 3I to a longitudinal bore 32 in drill steel i3, for the purpose of cleaning out the hole during a drilling operation.

The air system associated with distributing valve II, for the purpose of effecting reciprocation of piston hammer I2, comprises-an inlet air hose 34 connecting to the bottom of grip handle I4 and adapted to transmit air through a throttle valve 35 to an air passage 36 leading to the rear surface of valve chest 26. Throttle valve 35 may comprise a grip lever 31 pivotally mounted at the rear portion of handle I4 and adapted, when the handle is squeezed by thefoperator, to effect the depression of a stem 38 having a poppet 39 at its lower end, the poppet being spring pressed to upper or closed position as by a helical compression spring 4I seated adjacent the air inlet. When poppet 39 is depressed to open position due to squeezing of grip lever 31 against handle I4, air flows through passage 36 to a passage 42 in the rear Valve chest and then to the periphery of the valve element 28. Assuming that the valve 28 is in the forward position illustrated in Figure l, air is admitted to a chamber 43 in the rea-r valve chest, from which it flows through passages indicated schematically at 44 and 46 to chambers in advance of the piston I2. One such chamber, shown at 41, is dened by the back wall of distance piece I1 and the forward wall of the flange 48 of piston I2, while the other chamber comprises an annular groove 43 in distance piece i1 and communicating with certain flutes or keyways, to be described subsequently, on the stem I of the piston. Groove 49 communicates, as indicated at 52, with the air passage 46 from the distributing valve.

As the air pressure in advance of the piston increases, rearward travel of piston I2 is effected, and the air in a chamber 53 between piston flange 48 and forward valve chest 24 is initially exhausted through an'annular groove 54 in cylinder I6 which communicates through a passage 56 with a suitable exhaust vent, not shown, leading to the atmosphere. After the piston fiange 48 has traveled sufficiently far to block groove 54, the air in chamber 53 is compressed and transmitted through ports 25 to effect shifting of valve 28 to its rear position. The incoming air from air hose 34 and to the periphery of valve 28 is then caused to flow into forward valve chest 24, instead of through the path previously described, from which it flows through ports 25 to increase the pressure in chamber 53 and thus effect forward shifting of piston I2. An operation the reverse of that above described then occurs, with air from chamber 41 first exhausting through groove 54 and passage 56 and then increasing in pressure to effect, after the pressure is transmitted through passages 46 and 44 to chamber 43, the forward shifting of valve 28 to again reverse the operation. The piston I2 is thus pneumatically reciprocated, when the throttle valve 35 is open, to percuss the shank 22 of drill steel I3 at a frequency dependent upon the amount of air pressure admitted from air hose 34.

During operation of the piston hammer I2 as above described, the piston hammer, distributing Valve I I, and other elements of the drill are lubricated by admitting oil into the air stream flowing through passages 36 and 42. For this purpose, an oil chamber 58 is provided in the forward upper portion of handle I4 and adapted to communicate, through an annular groove 59 in the rear surface of valve chest 26, with the junction of passages 36 and 42. In order to permit replenishing of the oil supply in chamber 58, a suitable refill plug 6I is suitably mounted in the upper handle portion,

According to the present invention, the means for selectively effecting rotation of the drill steel I3 comprise, as shown in Figures 1 and 2, a ratchet ring 63 rotatably mounted in forward casing cylinder I8, stationary pawls 64 and 65 mounted in a rounded boss at the upper side of casing cylinder I8, and means 66 for shifting pawls 64 and 65 longitudinally of the drill to provide a cam action effecting their retraction out of engagement with the external teeth 68 of the ratchet ring. The pawls 64 and 65 are formed with relatively long cylindrical base portions 69 disposed longitudinally of the drill and at its right and left sides as viewed in Figure 2. Pawl bases 69 are mounted in corresponding journal bores 1I in casing cylinder I8, the journal bores openinginto chambers 'I2 to provide clearance room for the generally rectangular working or lug portions 13 of the pawls. As illustrated in Figure 2, the lugs 13 extend radially of their bases 69 and in a generally counterclockwise direction for engagement with the ratchet ring. The lugs are adapted to pivot either into the adjacent ratchet notches 14, as shown in the case of pawl 64 in Figure 2, or out of the notches as shown in the case of pawl 65 in Figure 2. The relationship between the pawls and ratchet ring 63 is one in which rotation of the ratchet ring in a counterclockwise direction is permitted, but rotation of the ratchet ring in a clockwise direction is effectively prevented by the pawls. In order to urge the pawl lugs 13 into the adjacent notches 14, volute springs 16, of the flat-wire type, are suitably mounted in bores in the upper or boss portion of cylinder I8.

The means 66 for shifting the pawls 64 and 65 longitudinally of the drill and to effect the retraction of pawl lugs I3 out of notches 14 and also out of engagement with ratchet teeth 58, comprise a cam cylinder 'I8 journaled transversely of the drill in the boss portion of cylinder I8 at the forward ends of pawl bases 69, spring return elements 19 mounted in a flange portion of distance piece I1 and adapted to urge the pawls forwardly into engagement with the cam cylinder, and a cam shoulder 8I provided on a forwardly extending rim or lip portion 82 of distance piece I1 and rearwardly adjacent the ratchet teeth 68. The cam cylinder 18 is formed with semi-cylindrical recesses 64 at the forward ends of pawl bases 69, the recesses being adapted to receive the pawl bases when they are shifted forwardly by-spring return elements 79. The forward ends of the pawl bases are thus spring pressed into engagement with semi-cylindrical cam portions 85 of the cam cylinder and may be shifted rearwardly when the cam cylinder is turned.

In addition to the recesses 84 described above, cylinder 18 is provided at its center with a pair of flats 86 and 81 (Figure 1) formed at right angles to each other and adapted to be engaged by a detent plunger 88 mounted in a longitudinal bore 89 in cylinder I8. Mounted around the stem of plunger 88 is a helical compression spring 9| which is seated between the forward or plug end of the plunger and a plug 92 which is threaded into the rear end of bore 89. The spring 9| operates to urge the associated plunger 88 into engagement with either of flats 86 or 81, so that cam cylinder 18 is retained in either of its two operating positions except when a control handle 93, at one end of the cam cylinder 18, is turned by the operator of the device. When the handle 93 is in the position shown in Figures 3 and 4, the pawl bases 69 are seated in flatwise engagement with the cam portions 85 of cylinder 18. When, however, the handle 93 is turned through a ninety-degree angle to the position shown in Figure 5, cam portions 85 are turned so that their edges, as distinguished from their fiats, are in engagement with the pawl bases. Pawl bases 99 are then shifted rearwardly a distance equal to the radius of cam cylinder 18, the spring return elements 19 then serving to bias the pawls in a forward direction to provide for subsequent return movement when the handle 93 is turned to its initial or Figure 4 po sition.

Referring particularly to Figures 3-5, the spring return elements 19 comprise cups 95 which are slidably mounted in longitudinal bores 96 in the upper portion of the flange 80 of distance piece I1. The cups 95 are resiliently urged in a forward direction by helical compression springs 91 seated at their forward ends in the cups and at their rear ends against the forward end of cylinder I6. The forward ends of bores 96 are necked down to provide seats for cups 95 but are sufciently large to receive rearwardly extending stem portions 99 of pawl bases 69. The stems 99 may therefore engage the bottom of spring cups 95 to shift the cups in a rearward direction, and compress springs 91, when the cam cylinder handle 93 is turned from the Figure 4 position to the Figure 5 position.

Upon reference to Figure 4 it will be seen that the lug portions 13 of cams 64 and 65 are of substantially the same dimensions, longitudinally of the drill, as the ratchet ring 63, but that the cylindrical pawl bases 69 are of substantially greater dimension and extend rearwardly from the rear ends of the lugs. It follows that when the pawls are in their forward positions, with the forward ends or pawl bases 69 seated atwise against the cam portions 85 of cam cylinder 18, the pawl lugs 13 will be in engagement with the full lengths of the adjacent ratchet teeth 68 and either in or out of the ratchet notches 14 as shown in Figure 2. According to the present invention, the turning of the handle 93 and cam cylinder 18 to the position shown in Figure 5, in order to shift the pawls 64 and 65 to their rear positions, effects retraction of the pawl lugs 13 out of engagement with ratchet teeth 68. This result is effected due to riding of the rear edges of the pawl lugs 13 up the cam shoulder 8| and into relatively small portions IOI of chambers 12 radially outwardly of distance piece rim 82. The pawls then remain in their retracted position, due to the previously described operation of detent plunger 88 and its associated spring 9|, until the cam cylinder handle 33 is again turned to the position shown in Figure 4, at which time the spring return elements 19 become operative .toshift the pawls 64 and 65 forwardly Ato the Figure 4 position. Pawl lugs 13 then ride down cam shoulder 8| and into engagement with the ratchet teeth 68 due to the action of the pawl springs 16, the latter being slidably engaged with lugs 13 in all positions of the pawls.l

Proceeding now with a description of the drill steel rotating elements associated with the pawl and ratchet mechanism, the ratchet ring 63 is provided at its inner portion with integral keys |03 which are suitably shaped to ride in corresponding right-hand spiral utes |04 in the forward portion of piston stem 5|. It follows that with each forward movement of piston hammer I2 the ratchet ring 63 will rotate counterclockwise as viewed in Figure 2, and that with each return or rearward piston movement the ratchet ring will tend to rotate clockwise. The latter movement, however, is prevented by the pawl lugs 13, so that the piston I2 itself must instead rotate counterclockwise to return the piston and ratchet ring to their initial relative positions. Referring to Figure 1, the mechanism for transmitting the rotational movement of piston I2 to the drill steel I3 comprises a chuck driver |06 mounted circumferentially of piston stem 5| and forwardly of ratchet ring 63, and a chuck |01 mounted circumferentially of drill steel shank 22 forwardly adjacent the chuck driver. The chuck driver |06 is longitudinally keyed, as indicated at |08, into the rear portion of chuck |01, and the chuck |01 is hexagonally bored to correspond to the hexagonal shape of drill shank 22. Accordingly, the drill steel will be rotated with the chuck driver |06. In order to effect rotation of the chuck driver with the piston I2, the chuck driver is formed with a pair of keys |09 adapted to ride in straight longitudinally extending flutes H0 in the forward portion of the piston stem. The keys |09 and flutes IIO operate to effect rotational movement of chuck driver |06 with piston I2 while permitting longitudinal movement of the piston stem 5| into percussive engagement with drill steel shank 22.

In order to stop the rotation of the piston I2, chuck driver |06, chuck |01 and drill steel I3, it is merely necessary to turn cam cylinder handle 93 to the position shown in Figure 5. The pawl lugs 13 are then longitudinally shifted and ride up cam shoulder 8| and out of engagement with ratchet teeth 68. The ratchet ring 63 then merely oscillates back and forth as the piston I2 reciprocates, and is inoperative to force the piston I2 and associated elements to rotate during the return piston stroke as is the case when the pawls are engaged with the ratchet teeth. With the pawls out of engagement with the ratchet, and with the ratchet ring 63 oscillating freely during forward and reverse movements of the piston hammer', there will be no rotation of the piston or of drill steel I3 but instead there will be only the hammer action desirable for hole spotting, chipping, etc.

To summarize the operation of the air hammer apparatus, let it be assumed that the air throttle valve 35 is closed as shown in Figure l, and that the pawl and ratchet elements are engaged as shown in Figures 2, 3 and 4. The grip lever 31 of throttle valve 35 is then squeezed to admit air through air hose 34 and poppet 39 to the distributing valve II, the latter being operative to alternately direct the air to the forward and rear sides of piston flange 48 and thus effect piston reciprocation. While the piston I2 is thus actuated forwardly and rearwardly to percuss the shank end 22 of drill steel I3, thevsteel is `7 rotated through apredetermined angle during each rearwardmovement Ycfthe piston.V This is because the ratchet. keys |03 ride inspiral flutes H34 during each forward piston movement to effect counterclockwise rotation of ratchet ring 83 as viewed in Figure 2. Since clockwise rotation of ratchet ring 63 is prevented by pawls I4 and 65 during the subsequent rearward piston movement, the stem 5I of piston I2 rotates counterclockwise to return the ratchet ring and piston to their initial rotated positions relative to .each

other. The rotary movement of piston I2 is transmitted through the straight flutes I and keys H39 to chuck driver |06, thence through key to chuck I'l, thence through the hexagonal locking relationship betweenchuck Il and drill steel shank 22 to eiect the rotation of drill steel I3. To prevent rotationof the drill steel, handle 93 of cam cylinder i3 is turned through a ninetydegree angle and to the position shown in Figure 5. The cam portions B5 then operate to shift the pawls 64 and 65 rearwardly through a distance equal to the radius of cam cylinder 18, with the stems 99 of the pawls pressing against the spring cups 95 to compress springs 91. As the pawls are thus shifted rearwardly, the rear edges of pawl lugs 'i3 ride up cam shoulder l8| to effect outward pivot of the pawls against the bias of pawl springs '16, until the pawl lugs are completely out of engagement with the ratchet teeth. Ratchet ring E3 then rotates-freely during each forward and return piston movement, and there is consequently no rotation either ofthe piston l2 or drill steel I3. To again start drill steel rotation, the cam cylinder handle B3 isl turned to the Figure L1- position, the springs 91 then being operative to shift pawls 64 and B5 forwardly and permit pawl lugs I3 to ride down cam shoulder 3i, under the bias of springs 1B, and into operative engagement with the ratchet teeth.

While the particular apparatus herein shown and described in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the detail of construction or design herein shown other than as defined in the appended claims.

I claim:

l. A pneumatically operated hammer apparatus, comprising an elongated casing, a drill steel mounted longitudinally of said casing and projecting from the forward end thereof, a piston mounted longitudinally of said casing for reciprocatory movement toward and away from said drill steel to percussively actuate the same, a ratchet ring mounted in a plane generally perpendicular to said casing, a pawl element operably associated with said ratchet ring, means to define a cam surface adjacent said pawl element, means to operably associate said ratchet ring and pawl element with said piston and drill steel to transform the reciprocatory motion of said piston into rotary motion of said drill steel, and means to shift said pawl element longitudinally of said casing and along said cam surface to provide a cam action disengaging said pawl element from said ratchet ring and effecting interruption of drill steel rotation.

2. A pneumatically operated hammer apparatus, comprising an elongated casing, a drill steel mounted longitudinally of said casing and projecting from the forward end thereof, a piston mounted longitudinally of said casing for reciprocatory movement toward and away from said ,drill steel to percussively actuate the same, a ratchet ring mounted in a plane generally perpendicular to said casing, a pawl associated with said ratchet ring and movable along an axis lying longitudinally of said casing, said pawl being also pivotable about said axis into and out of engagement with the teeth of said ratchet ring, a cam shoulder provided in said easing adjacent said pawl, means to operably associate said pawl and ratchet ring with said piston and drill steel to transform the reciprocatory motion of said piston into rotary motion of said drill steel, and means to shift said pawl along said axis and into engagement with said cam surface to effect pivoting `of said pawl about said axis and out of operativeengagement with said ratchet ring teeth, said arrangement permitting interruption of drill steel rotation through manual operation of said last-named means.

3. The invention as claimed in claim 2, wherein resilient means are provided to bias said pawl toward its operative position in engagement with said ratchet ring teeth.

4. The invention as claimed in claim 3, wherein said resilient means comprise a first spring adapted to shift said pawl along said longitudinal axis, and a second spring adapted to pivot said pawl about said axis.

5. A rotation release device for a pneumatically operated hammer apparatus having an elongated casing, a drill steel mounted generally axially of said casing and projecting from the forward end thereof, and a piston hammer mounted axially of said casing for reciprocation toward and away from said drill steel to percussively actuate the same; which comprises a ratchet ring, a pawl mounted radially adjacent said ratchet ring, said pawl having a cylindrical base journaled longitudinally of said casing and slidable longitudinally thereof, said pawl also having a lug portion projecting radially from said base and rotatable and longitudinally slidable therewith, means to effect operative engagement between said lug portion and the teeth of Saidratchet ring when said pawl is in one longitudinal position, cam means to effect rotation of said lug portion away from said ratchet ring teeth as said pawl is shifted longitudinally of said casing to a second longitudinal position, and means to operatively relate said piston, pawl, ratchet ring and drill steel to effect rotation of said drill steel when said pawl is in said one longitudinal position.

6. The invention as claimed in claim 5, wherein said cam means comprises a rst cam element movably mounted at one end of said cylindrical pawl base and adapted to effect longitudinal shifting thereof, and a second cam element fixedly mounted adjacent the outer edge of said pawl lug portion and relatively adjacent the outer end of said pawl base, said second cam element being shaped to cooperate with said outer edge of said pawl lug portion to pivot the same out of engagement with the teeth of said ratchet ring during longitudinal shifting of said pawl base by said first cam element.

7. The invention as claimed in claim 6, wherein a iirst spring is provided longitudinally adjacent said pawl base to bias the same to its initial longitudinal position, and a second spring is provided radially adjacet said pawl lug portion to bias the same toward said ratchet teeth.

8. The invention as claimed in claim 6, wherein a. detent mechanism is associated with said first cam element to maintain it in its various operating positions.

9. An air hammer apparatus, comprising an elongated generally cylindrical casing, a piston mounted in said casing and slidable longitudinally thereof, said piston having a flange disposed in the rear portion of said casing and a stem extending forwardly and axially of the mid-portion of said casing, a distributing valve mounted in the rear portion of said casing and adapted to transmit air from a source of air pressure and alternately to the forward and rear sides of said piston flange to thus eiect reciprocation of said piston, chuck means rotatably mounted in the forward portion of said casing and adapted to receive a drill steel, rst key means associating said chuck means and piston stem to eiect rotation of said chuck means and drill steel with said piston while permitting percussive actuation of said drill steel by said piston stem, an externally toothed ratchet ring mounted concentrically around said piston stem, second key means associating said ratchet ring and piston stem to eect relative rotation between said ratchet ring and piston during reciprocation of said piston, a pawl mounted in the mid-portion of said casing radially outwardly of said ratchet ring, said pawl being pivotable about and slidable along an axis parallel to said piston stem, spring means to pivot said pawl into operative engagement with the teeth of said ratchet when said pawl is in one longitudinal position, a cam shoulder provided in said casing longitudinally adjacent said pawl, and means to shift said pawl along said axis to a second longitudinal position at which said cam shoulder is operative to maintain said pawl in a position pivoted out of engagement with said ratchet teeth.

l0. The invention as claimed in claim 9, wherein said rst key means comprise a key provided on said chuck means and adapted to slide in a straight flute on said piston stem, and said second key means comprise a key provided on said ratchet ring and adapted to slide in a spiral flute on said piston stem.

11. The invention as claimed in claim 9, wherein second spring means are provided to bias said pawl toward said one longitudinal position.

References Cited in the le of this patent UNITED STATES PATENTS Number 

